Device for determining distance and for transmitting data in a motor vehicle

ABSTRACT

A device is proposed for ascertaining distance and transmitting data in a motor vehicle. It has a transmitting arrangement for generating and emitting a radar signal. A receiving arrangement receives a radar signal. It is characterized in that switchover arrangements are provided which cause the transmitting and/or receiving arrangement to operate either in a radar operating mode for detecting the distance and/or speed of a further object, or in a data-exchange operating mode for the exchange of data with a transceiver. Specific functions are enabled in dependence on the data exchange.

FIELD OF THE INVENTION

The present invention relates to a device for ascertaining distance andtransmitting data in a motor vehicle.

BACKGROUND INFORMATION

A system for measuring distance and the selective transmission ofinformation for motor-vehicle applications is described in GermanPublished Patent Application No. 44 42 189. The transmitting andreceiving units provided for the distance measurement are at the sametime used for transmitting and receiving information and/or the signalsused for the distance measurement are utilized directly for the transferof information. With the aid of the distance measurement, passiveprotective measures for vehicles can be activated in response to afront, side or rear collision. The information exchange is used forassessing traffic situations, or for detection, identification and costallocation for a road toll.

SUMMARY OF THE INVENTION

An object of the present invention is to develop the transmissionchannel, present for the distance measurement, for further motor-vehiclefunctions which are only activated in conjunction with a data exchangedeemed as valid.

The device for ascertaining distance and transmitting data in a motorvehicle has a transmission arrangement for generating and emitting aradar signal. It is equipped with a receiving arrangement for thereception of a radar signal for detecting the distance and/or the speedof a further object. The device of the present invention has thedistinction that a switchover arrangement are provided which cause thetransmitting and/or receiving arrangement to operate either in a radaroperating mode for determining distance and/or speed of the furtherobject, or in a data-exchange operating mode for the data exchange witha transceiver, specific motor-vehicle functions being enabled as afunction of the data exchange. These motor-vehicle functions can be amaster-key system or the cancellation of a vehicle immobilizer.According to the present invention, the transmitting and receivingarrangement, present anyway for ascertaining the distance or speed, arealso used for the purpose of exchanging data with an optionally portabletransceiver. The data exchange with the transceiver is evaluated for anauthorization. If the receiving arrangement receives a data signal,recognized as valid, from the transceiver, then, for example, themaster-key system is activated along the lines of unlocking. If the dataexchange proceeds within the motor vehicle, then it can be utilized toquery the driving authorization of the user with the aid of thetransceiver carried along. The start enablement is only granted inresponse to a transceiver signal recognized as authorized. Byintegrating the additional function of the data exchange for the purposeof the access authorization and start authorization, existing componentswhich are already provided for implementing other functions can likewisebe utilized. With the aid of the switchover arrangement, the differentoperating modes of the transmitting and receiving arrangement can bespecifically selected depending on the operating situation. In the radaroperating mode, the distance and/or the speed of the vehicle withrespect to an adjacent object is/are ascertained. These data can beutilized for triggering an airbag, for controlling a warning device inconnection with a Park Pilot system, detection of objects in theso-called dead angle, and stop-and-go detection. An emission of theradar signal into the passenger compartment of the motor vehicle can beevaluated for the purpose of monitoring the passenger compartment inconjunction with a car alarm or a seat-occupant detection.

In one expedient refinement, the data-exchange operating mode isactivated when the motor vehicle has been switched off and/or the userhas left the motor vehicle. At this point, the transmitting andreceiving arrangement are controlled, such that they are able to sendand/or receive and evaluate a data signal. Namely, to unlock themaster-key system, an appropriate data signal is expected from thetransceiver.

In another refinement, the data-exchange operating mode is activatedwhen a switching element has been actuated, for example, in conjunctionwith the initiation of an unlocking operation and/or start of the motorvehicle. For instance, upon actuation of the ignition switch, aswitchover is made to the data-exchange operating mode. In order for theenablement to be granted for starting the motor vehicle, it is necessaryfor the transmitting and receiving arrangement and the transceiver tohave run through a data exchange recognized as valid. If the dataexchange is to be evaluated for the purpose of unlocking the motorvehicle, the user, for example, actuates the door handle of the motorvehicle. The switching signal recognized in this connection brings abouta switchover into the data-exchange operating mode, so that data can nowbe exchanged with the transceiver. If the data exchange is run throughsuccessfully, the master-key system is activated along the lines ofunlocking.

In one advantageous refinement, the switchover arrangement is controlledin the manner that they are used for information coding. Thus, a dualfunction is ensured. First of all, the switchover can consequently beimplemented; on the other hand, in the data-exchange operating mode, theswitchover arrangement are used as a modulation arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram.

FIG. 2 shows a first view of one possible arrangement and networking inthe motor vehicle.

FIG. 3 shows a second view of the one arrangement and networking in thevehicle.

FIG. 4 shows a first schematic, circuit-engineering implementation ofthe device according to the present invention.

FIG. 5 shows a second schematic, circuit-engineering implementation ofthe device according to the present invention.

DETAILED DESCRIPTION

A transmitting/receiving device 10 emits a radar signal and receives aradar signal. Transmitting/receiving device 10 is able to exchange adata signal with a transceiver 16. Transmitting/receiving device 10exchanges signals with a control unit 12. Indicated schematically, aradar operating mode 17 and a data-exchange operating mode 19 areimplemented in control unit 12. Either radar operating mode 17 ordata-exchange operating mode 19 can be activated via a switchoverarrangement 15. Control unit 12 exchanges data with further functioncontrol units 18 by way of a bus system 14.

According to the exemplary embodiment as shown in FIG. 2,transmitting/receiving devices which take in the external space of themotor vehicle are arranged around it. Transmitting/receiving devices 10,preferably located at the front and rear, as well as in the side-doorarea, are networked via bus system 14 and are connected to control unit12 and function control unit 18.

In the exemplary embodiment according to FIG. 3, at least onetransmitting/receiving device 10 is arranged in the passengercompartment, e.g. at the inner door post, and is aligned such thatsignals can be emitted into and received from the passenger compartment.Transmitting/receiving devices 10 exchange signals with control unit 12,which is optionally coupled to further function control units 18 via bussystem 14.

A clock-pulse generator 24 emits its output signal to a first pulsegenerator 26 and to a time delay 28. The output signal of time delay 28is fed to a second pulse generator 27. The output signal of first pulsegenerator 26 is the input variable of a first switchover arrangement 21which is controlled as a function of an output signal of control unit12. The output signal of first switching element 21 is used as acontrolled variable for a first switching element 31. An oscillator 34,optionally likewise influenced by control unit 12, emits its outputsignal via a power divider 36 and first switching element 31 to atransmitting antenna 40. The output signal of adjustable time delay 28is used as input variable for a second pulse generator 27 whose outputsignal is fed to a second switchover arrangement 22 that is likewisecontrolled by control unit 12. The output signal of second switchoverarrangement 22 is used as controlled variable for a second switchingelement 32. The second output signal of power divider 36 is supplied viasecond switching element 32 to a mixer 38. A signal received by areceiving antenna 42 forms the second input variable of the mixer. Mixer38 emits an output signal 44.

The exemplary embodiment according to FIG. 5 is a very simplifiedspecific embodiment compared to FIG. 4. The output signal of oscillator34 is supplied directly to mixer 38. The second input/output of mixer 38is connected to transmitting antenna 40 and receiving antenna 42,respectively. Depending on the control, mixer 38 is fed a further inputsignal, or is tapped as mixer output signal.

Radar operating mode 17 and data-exchange operating mode 19 are storedin control unit 12. Radar operating mode 17 is used for ascertaining thedistance and speed, respectively, of the motor vehicle in relation tofurther objects. To that end, a short radar pulse is emitted, and thereflection wave subsequently coming in again is evaluated with regard tothe propagation time difference. The distance to objects and theirrelative speed can be determined on the basis of the propagation timedifference. If a plurality of measurements are carried out, the speed isdetermined through differentiation of the distance. In the case of onlyone measurement, the speed can be derived with the aid of the Dopplereffect.

Switchover arrangement 15 makes a selection between radar operating mode17 and data-exchange operating mode 19. In the data-exchange operatingmode, transmitting/receiving device 10, through an appropriate coding,frequency modulation or phase modulation, is able to transmit andreceive data signals. Data are exchanged with transceiver 16. Within theframework of an authorization query, the data signal sent by transceiver16 is received and evaluated as to whether it agrees with a referencesignal deemed as valid. Motor-vehicle functions are activated, i.e.enabled as a function of this legitimacy check of the signal received indata-exchange operating mode 19. A signal recognized as valid causes themaster-key system to lock or unlock. Within a driving authorizationquery, this authorization is only granted when a transceiver 16,recognized as valid on the basis of the data exchange, was present inthe passenger compartment of the motor vehicle. In data-exchangeoperating mode 19, the energy necessary for carrying out thetransmission process can also be provided to transceiver 16, so that itdoes not have to have its own energy supply.

In the exemplary embodiment according to FIG. 2, transmitting/receivingdevices 10 are arranged in such a way that they take in the externalspace of the motor vehicle. In radar operating mode 17, the reflectedradar signals at low speeds, —e.g. less than 30 km/h—are evaluated for aPark Pilot system. If a specific distance to an adjacent object isexceeded, a warning signal is generated which signals a collision dangerto the user. In this operating mode, the distance is detected. In“stop-and-go” operation, radar operating mode 17 can likewise be used inthe case of a traffic jam to signal to the driver the stopping orcontinuation of driving by the person in front, or to cause thisautomatically. As a further application case, with the aid of radaroperating mode 17, the airbag can be triggered when the vehicle isstationary for protection against striking vehicles.

At higher speeds—e.g. greater than 30 km/h—the reflected radar signal isevaluated for early crash detection. For example, airbag triggering canbe initiated if an imminent crash is detected based on these signals.

The switchover from radar operating mode 17 to data-exchange operatingmode 19 is preferably made when the vehicle is at a standstill, in orderto unlock a locked vehicle with the aid of transceiver 16. Theoperating-mode switchover can be triggered by various events. First ofall, transmitting/receiving device 10 can be switched periodically toreceive mode. Alternatively, data-exchange operating mode 19 isactivated by pulling on the door handle with the actuation of theappropriate switching contact.

Transmitting/receiving device 10 exchanges data with transceiver 16 inthe form of information-coded signals in, for example, the gigahertzrange. Transmitting/receiving device 10 sends information to transceiver16 which sends it back to transmitting/receiving device 10 furtherprocessing. The incoming response from transceiver 16 is checked forvalidity in control unit 12. If the received signal agrees with thatwhich is expected, then a function control unit 18, configured as amaster-key-system control, is activated in conjunction with bus system14 along the lines of unlocking the master-key system.

However, in data-exchange operating mode 19, it is not necessary thattransmitting/receiving device 10 itself transmit data. It could besufficient merely to receive the data emitted after actuation of aswitching element on transceiver 16. However, security againstmanipulation is increased when the data exchange is bidirectional. Inthis embodiment, a propagation-time measurement can be provided as afurther validity criterion. If the signal sent by transmitting/receivingdevice 10 is returned merely by one transceiver 16, this return reply isdelayed by filter transient times, times for switchover processes andthe transmission time of the signal through space. Were a furthertransceiver 16 also to participate, unauthorized, in the data exchange,then the use of a further transceiver 16 would imply a further timedelay in the reply signal. With the aid of a propagation-timemeasurement, only one reply delay is permitted which comes about whenusing a single transceiver 16 within a distance considered as valid. Ifthe reply-signal delay exceeds a specific time threshold, a replysignal—possibly authorized—coming in after that does not initiate anunlocking operation. Since an arrangement for determining propagationtime are already provided in radar operating mode 17, it is possible tofall back upon this arrangement to determine propagation time indata-exchange operating mode 19, as well. In addition, the signal sentout in data-exchange operating mode 19 can be used for the energy supplyof transceiver 16, so that energy for the subsequent transmissionprocess of transceiver 16 is buffered for a short time.

Transmitting/receiving device 10 can preferably be activated by turns inradar operating mode 17 and in data-exchange operating mode 19, in orderto check the plausibility of an unlock demand. In radar operating mode17, it is determined whether an object is approaching the vehicle. Onlyin response to an approach is the unlock operation actually initiated.Thus, possibilities for manipulation can be further restricted.

In the exemplary embodiment according to FIG. 3, transmitting/receivingdevices 10 are so arranged that they emit signals into the vehiclepassenger compartment and receive signals from the vehicle passengercompartment. The two operating modes, radar operation and data exchange,are again provided for this application case, as well. When the vehicleis switched off and locked, transmitting/receiving devices 10 arecontrolled periodically in radar mode to monitor the passengercompartment. If, from the reflected radar signals, a person is detectedin the passenger compartment, then the alarm is activated. On the otherhand, in travel operation, the arrangement in radar operating mode 17determines which vehicle seats are occupied to, if necessary, trigger anairbag only for the occupied seats. A triggering is prevented when theradar signals indicate a child's seat. The switchover from radar mode 17to data-exchange mode 19 is made when the user steps into the vehicle.To this end, for example, the corresponding opening and closing signalsof the door, or a pulling on the door handle can be evaluated. Theoperation of the ignition switch for starting up the motor vehicle couldalso effect the change into data-exchange operating mode 19. Indata-exchange operating mode 19, a data exchange betweentransmitting/receiving device 10 and transceiver 16 proceeds in asimilar manner as already described for the exemplary embodimentaccording to FIG. 2. If a signal sent out by transceiver 16 isrecognized as valid, control unit 12 generates a suitable enable signalwhich is routed via bus system 14 to control units 18 which are relevantfor the operation. The motor vehicle can thereupon be started, sincefunction control units 18 are now switched so that they are ready foroperation.

Clock-pulse generator 24 generates a pulse signal at a frequency of 1 to50 MHz. First and second pulse generators 26, 27, with the aid of “steprecovery diodes” or switching transistors, convert these triggeringpulses into short pulses having a duration of less than 1 nanosecond.Adjustable time delay 28, downstream of which is likewise a second pulsegenerator 27, is used to generate a reference signal. The resultingpulse is accordingly time-delayed compared to the output signal of firstpulse generator 26. In radar operating mode 17, first and secondswitching elements 21, 22 are controlled by control unit 12 along thelines of a closing. Because of this, the pulse is routed directly to thecontrol input of first and second switching elements 31, 32. With theappearance of the pulse, first and second switching elements 31, 32 areclosed for this pulse duration. For this time span, the keyed outputsignal of oscillator 34, e.g. an oscillator in the 2.45 GHz, 5.8 GHz, 24GHz or 77 GHz range, reaches transmitting antenna 40 via power divider36. The radar pulse is so short that only a few wave trains ofoscillator 34 are transmitted. These wave trains also arrive in atime-delayed manner at the local oscillator input of mixer 38. Thissignal is correlated with the signal received by receiving antenna 42.The output signal of mixer 38 is evaluated in a signal analysis (notshown) with respect to distance and relative movement.

In data-exchange operating mode 19, first and second switchoverarrangements 21, 22 are controlled in accordance with the information tobe transmitted or to be received. The information is binary coded, inthat first switchover arrangement 21 is opened and closed depending onthe bit sequence of the code to be sent. In the open state, the twoswitchover arrangements 21, 22 apply an output potential (switchingsignal) to the respective control input of switching elements 31, 32, sothat they are controlled along the lines of a closing. In conformitywith this binary coding, first switching element 31 routes the outputsignal of oscillator 34 to transmitting antenna 40. In data-exchangeoperating mode 19, second switchover arrangement 22 remains open, whicharrangement second switching element 32 is controlled along the lines ofa closing. The oscillator signal is applied constantly to mixer 38. Theinput signal acquired by receiving antenna 42, this input signallikewise being binary coded in a corresponding manner, is mixed with theoscillator signal. The output signal of mixer 38 is decoded by a signalacquisition (not shown) and evaluated by comparison with a referencesignal for the purpose of checking the authorization.

In data-exchange operating mode 19, second switchover arrangement 22 iscontrolled by control unit 12 along the lines of an opening, so that theoscillator output signal is applied at the mixer input via secondswitching element 32 which is then closed. This mixer activation is notsuitable for the radar-pulse evaluation. At least second switchoverarrangement 22 is influenced as a function of a switching signal of anoperating element or monitoring sensor. For example, with the pulling ofthe door handle, operation of the ignition switch, or after a detectedopening or closing of the door, second switchover arrangement 22 isopened, since at this point, an authorization query with correspondingreception of coded information from transceiver 16 is expected indata-exchange operating mode 19.

In an alternative embodiment, the data can also be transmitted with theaid of a frequency modulation or phase modulation. Control unit 12causes a frequency modulation or phase modulation of oscillator 34 as afunction of the information.

A sketch is shown, simplified compared to FIG. 4, when onlydata-exchange operating mode 19 is necessary. As already describedabove, the system is used as a receiver. However, if a basebandmodulation is applied at port 44 of mixer 38, then this system can alsobe used as a transmitter. As a supplement to the system according toFIG. 4, the data transmission can be carried out by baseband modulationat port 44 there, as well.

If, for example, transmitting/receiving devices 10 are installed in thedoor frames, then the direction of beam can be changed from thepassenger compartment to the external space by suitable switchover ofantennas 40, 42. This could be achieved by “phasing lines”, switchingover the antennal elements, or by beam forming using two major lobes. Ajoint transmitting/receiving antenna 40/42 is possible in principle.

Further uses of the circuit arrangement described above can beimplemented in data-exchange operating mode 19. To that end, transceiver16 is arranged in a stationary manner in order, as a function of asignal recognized as valid, to activate a device which frees theentrance to a parking lot, multi-story car park, garage, camping site,car ferries, motorails or the like. The user must actuate an appropriateoperating element which initiates the switchover from radar operatingmode 17 into the data-exchange operating mode along the lines describedabove. If is a code recognized as valid is received by stationarytransceiver 16, a barrier, a gate or the like is activated in thedesired manner.

In addition, the data exchange can be used for debiting fees from anaccount and/or for access authorization, for example, at parking lotsand gas stations.

The relevant diagnostic data stored in the vehicle could likewise beread out in data-exchange operating mode 19 when the vehicle is in theservice station for inspection or repair purposes.

Also to be considered as a further application of data-exchangeoperating mode 19 is the communication with transceivers 16, disposed atthe edge of the roadway, for transmitting traffic information.

In a further alternative application in data-exchange operating mode 19,data can be exchanged in a wireless manner with further devices such asa driver information system, a mobile telephone or a computer located inthe vehicle. Thus, a warning message generated by the alarm system couldbe routed automatically via the mobile telephone to a desired mobiletelephone terminal connection.

By using various data structures and protocols, the above-indicatedapplications can be selectively addressed in data-exchange operatingmode 19 with the same communication elements.

What is claimed is:
 1. A device for ascertaining a distance and transmitting data for a motor vehicle, comprising: a transmitting arrangement for generating and emitting a radar signal; a receiving arrangement for receiving the radar signal; and a switchover arrangement for causing at least one of the transmitting arrangement and the receiving arrangement to operate according to one of: a radar operating mode for detecting at least one of the distance and a speed of at least one further object, and a data-exchange operating mode for a data exchange with a transceiver, wherein: at least one of a drive authorization and an access authorization of the motor vehicle is released in dependence on the data exchange in the data-exchange operating mode.
 2. The device according to claim 1, wherein: the data-exchange operating mode is activated at least one of when the motor vehicle is switched off and when a user has left the motor vehicle.
 3. The device according to claim 1, wherein: the data-exchange operating mode is activated as a function of an actuation of an operating element in conjunction with an initiation of at least one of an unlocking operation and a start operation.
 4. The device according to claim 1, wherein: a specific function is enabled only when a signal detected in the radar operating mode indicates an approaching object.
 5. The device according to clam 1, wherein: the switchover arrangement is activated for coding information to be transmitted in the data-exchange operating mode.
 6. The device according to claim 1, further comprising: an oscillator for providing an oscillator signal; a transmitting antenna; and a switching element via which the oscillator signal can be routed to the transmitting antenna, wherein: a pulse signal for generating the radar signal is relayed via the switchover arrangement for a control of the switching element.
 7. The device according to claim 1, wherein: the switchover arrangement is controlled as a function of information to be transmitted.
 8. The device according to claim 1, wherein: in the data-exchange operating mode, a signal propagation time, upon which an enablement of a specific motor-vehicle function depends, is determined as a function of a transmitted and a received signal.
 9. The device according to claim 1, further comprising: an oscillator for providing an oscillator signal; and a mixer, wherein: the receiving arrangement includes a receiving antenna that receives the radar signal, the mixer correlates the radar signal with the oscillator signal, and a specific function is enabled in dependence on an output signal of the mixer.
 10. The device according to claim 9, further comprising: another switchover arrangement, wherein: the oscillator signal is applied at an input of the mixer as a function of the other switchover arrangement.
 11. The device according to claim 9, wherein: the oscillator signal is applied at an input of the mixer in the data-exchange operating mode.
 12. The device according to claim 1, wherein: an actuator of a smart master-key system is controlled as a function of the data exchange in the data-exchange operating mode. 